Adding value to farm pond implementation with geospatial information

Adding value to farm pond implementation with geospatial information

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Vinit Raskar
Watershed Organisation Trust
Pune, India

The government of India has started the practice of farm ponds across the country to ensure water security for farming and particularly for horticulture. Here’s a look at how geospatial information has added value to this activity under Climate Change Adaptation project in Maharashtra

Introduction
Water harvesting is one of the key components of successful rainfed farming in semi-arid regions which becomes more relevant in erratic weather. Harvested excess run-off during high rainfall days can be used during the dry spell for irrigation. Several programmes of the Government of India like RADP (Rainfed Area Development Programme), NHM (National Horticulture Mission), MGNREGS (Mahatma Gandhi National Rural Employment Guarantee Scheme) and IWMP (Integrated Watershed Management Programme) have farm pond as one of the important components. To ensure water security for farming and particularly for horticulture, the government has started the practice of farm ponds across the country.
Construction of appropriate water conserving structures like farm ponds ensures protective irrigation, hence, in order to increase the area under irrigation, both seasonally and perennially, means of lifting water (pumps) from the nala / valley to the upland fields needs to be considered, as also to include farm ponds to increase water availability. This is important in the face of the challenges of a varying climate. Keeping the above points at the forefront, Watershed Organisation Trust (WOTR) has planned and started implementation of farm ponds along with regular soil-water conservation (SWC) work under Climate Change Adaptation (CCA) project in selected regions of Maharashtra.

Approach, study area and methodology
As mentioned earlier, supplementary irrigation management plays an important role to fulfill the demand of irrigation for agriculture. Efficient rain water management is necessary to improve water productivity and protect the natural resource base in rainfed regions. Farm ponds can help the farmers in farm water management by using stored water for tackling the drought or dry spells. Farm pond is a climate resilient technology for rainfed agriculture.

Plan of approach
Farm pond implementation was divided into following key components:
1. Understanding the property of land and topography including study of soil properties, slope and land-use land-cover of project area.
2. Identification of geology and ground water dynamics including study of broad geological mapping, aquifer mapping hydrogeology and groundwater movement mapping of project area.
3. Identification of potential sites for farm pond implementation including lithology mapping, existing water harvesting structures mapping, recharge-discharge zone mapping.
4. Identifying target group of farmers for social mobilization including location specific farmer mapping, low and high priority zone mapping.
5. Implementation of farm ponds.
For all the above mentioned components, geospatial tools were used. All these components play an important role in farm pond implementation, so, systematic approach was adopted.

Project area
CCA project is being implemented in six states of India, whereas farm ponds are planned to be implemented in 29 villages of Sangamner and Akole talukas of Ahmednagar district of Maharashtra state. The implementation is funded by NABARD (National Bank for Agriculture and Rural Development). For the sake of convenience, these 29 villages are divided into 3 zones namely Pathar I, Pathar II and Akole cluster. Agro-climatically, Pathar I and Pathar II fall into scarcity zone and Akole into transition zone.

Map 1: Location map of Project area for Farm Pond Implementation.

Methodology
The following steps were involved in the project implementation:
Soil map generation: Survey number wise net plan was used for soil map generation.

Map 2: Soil depth of project area collected in net planning
Aquifer mapping: Delineation of aquifers was done on the basis of hydrogeological factors such as basalt geometry, weathering and fracture patterns, water level data and geomorphology. Generally, weathered vesicular-amygdaloidal basalts superposed on fractured compact basalt constitute good aquifers across the Deccan Volcanic province. Based on above system of openings, nine aquifer systems were identified in Akole cluster and 11 aquifer systems in Pathar cluster.

Mapping and attribution of all water harvesting structures: This exercise includes mapping of major drainage line treatments like check dams, gabions, dug wells, bore wells, percolation tanks etc. This was done using GPS.


Map3: Showing Water Harvesting Structure in selected villages of Pathar I and Pathar II.
Mapping of agricultural land along with ownership of the plots: This exercise was carried out in four villages and purpose of doing this was to map exact agricultural land in villages so that farm pond sites will be marked in agriculture area and not in wastelands. Ownership of the plots used in identifying farmers, most suitable for form pond implementation and accordingly social mobilization was carried out.

Map4: Mapped agricultural plots with plot ownership.

Contour-wise lithologic units map generation: For this, contours generated at 5 meter interval were taken. Their grouping was done in compact basalt and vesicular basalt based on field observation and hydrologist knowledge. Grouping was made like 740-765m is vesicular basalt, 765-770m compact basalt, 770-780 vesicular basalt, 780-790 compact basalt etc. Maximum identification was done till 1000m as beyond that, the area was not found suitable for farm pond implementation.

Map5: Contourwise lithological units for Warudi Pathar village from Pathar II Cluster.

Superimposition of all dataset to identify potential farm pond locations: All the datasets were then superimposed on each other and based.
Farm pond locations were identified based on the following parameters:
• Recharge and discharge zones
• Agricultural land
• Water resources
• Accessibility

Map6: Locations of proposed farm ponds in Warudi Pathar village of Pathar II
Cluster
After identification of sites it was necessary to have list of farmers for social mobilisation. Social mobilization is the identification of farmers for farm ponds implementation. Identification of farmers was done at the following levels.
i.Farmers whose plots are having identified as having farm ponds.
ii.Farmers falling in 50 metres buffer of proposed sites.
For this, ownership mapping data was used which was collected using mobile GPS.

Map7: Farmer identification for proposed farm pond location.

Map8: Plots and Farmers falling in 50m buffer of Farm Ponds.
The purpose behind taking farmers in the 50m buffer is to maintain proposed technical site of farm pond. Drawing the buffer gives choice of more than one farmer, so, if one farmer is not ready to implement farm pond due to any issue, field team can move to another farmer. Along with maps, a preference-wise list of farmers was provided to the field team to have choice of farmers (but keeping technical sites constant).

Findings
The following are the findings from farm pond implementation study:
• The sites identified on the basis of GIS proved to be useful for supplemental irrigation in case of water stress.
• It helps in ground water recharge in nearby areas. It was observed that the water level of nearby wells increased.
• It was learnt that the marginal farmers give priority to small size (10 x10 x 3m) structure due to low investment and land size required.